Machine for grinding knife blades



May 29, 1945. c, BROWN 2,377,126

MACHINE FOR GRINDING KNIFE BLADES Filed 001;. 20 1943 3 Sheets-Sheet l lJU {If 42 3.0 MIME/V708 Y afiaigsiBr-awn v ATf RA/EY May 29, 1945. F, BROWN 2,377,126

MACHINE FOR GRINDING KNIFE BLADES Filed Oct. 20, 1943 3 Sheets-Sheet 2 8 N 2 m2 2q #0 I 1 yo 42 84 m- W 4 I f"7 ""7" 7 f. I I 3 20 I0 6 I 66 Zz INVENTOR Crarl'as 71B madly ATTORNEY May 29,1945. c. F. BROWN 2,377,126

MACHINE FOR GRINDING KNIFE BLADES Filed Oct. 20, 1943 3 Sheets-Sheet 3 Patented May 29, 1945 UNITED STATES PATENT OFFICE MACHINE FOR GRINDING KNIFE BLADES Charles F. Brown, Greeneville, Tenn. Application October 20, 1943, Serial No. 507,224

7 Claims.

My invention relates to machines for grinding knife blades, and particularly to machines for sharpening the curved blades of mowing-machines which are commonly used for cutting the grass of lawns.

The objects of m invention are to provide a machine for sharpening mowing-machine blades of different weights with abrasive wheels of dif ferent types; to produce high centers in both reel-blades and cutter bars for end clearance; to provide for the quick adjustment of the grinding mechanism to the reel the blades of which are to be sharpened; to provide a positive control and adjustment forthe cut on both ends of the reel-blade; to provide for the setting of the proper relief of the cutting edge of the reel-blade; to provide for the sharpening of the reel-blades of standard mowing machines without the removal of the reel from the machine; to provide for the quick reversing. of the travel of the abra sive-wheel for the quick grinding of hard spots in a blade; and to provide other refinements of control and of adjustment of the reel-blade and of the abrasive-wheel.

In the drawings, which form a specification:

Figure I shows; in plan, my machine set for the sharpening of the reel-blades of a small mowing machine;

' Figure II is an end view, partly in section, of the machine shown in Figure I;

Figure III is a detail in plan of the track adjustment;

Figure IV is a longitudinal section on line a in Figure III;

Figure V is a detail, in elevation, of the bladeguide;

Figure VI is an end elevation of the bladeguide shown in Figure V;

Figure VII shows in part, and in plan, the grinder mechanism arranged for use with an abrasive cup-wheel.

In Figures I and II the numeral 2 indicates the two heads of a lawn-mower, spaced apart by the bar 4. The reel-blades 6 and l are supported by spiders on the rotating shaft 8. The supporting spiders are not shown on the drawings as their character and position are well known, and as their inclusion in the drawings is not necessary.

At ID, ID are base plates, preferably of channel form for the sake of stiffness, and on which are adjustably mounted brackets l2 and I4 and track chairs it. .These brackets and track chairs are part of this plates l0, and are secured in position in the usual manner by bolts I8, 20, and 22, which pass through slotted openings in the base plates Ill.

The bracket 12 supports a pivoted arm 24, pivoted at 26, and secured in position when adjusted by bolts and wing-nuts 28. At the tops of these arms 24 are cut any convenient and suitable rests 29 for the bar 30, which bar extends from one bracket l2 to the other. The bar 30 may be held in any pair of the rests 29, and in any suitable manner.

Adjustable clamping-hooks 32, 32 are secured to the bar 30 and to the mower bar 4. They are secured to the bars by means of keys or wedges 36, and they are adjustable as to their length by the bolt connection 38 in the slots 40.

The brackets l4 carry vertically adjustable bearings 42, secured after adjustment by the studs and bolts 44 in the upright back of the bracket. The bearing 42 is adjusted, after looscning the bolt 44, by means of the micrometer screw 46 which turns in a threaded hole 48 in the body of the bearing, the screw 46 being surmounted by a milled head 50 for convenience in turning it.

Carried by the bearings 42 is a bar 52, which.

may be solid or a piece of pipe as shown. The bar 52 carries two or more clamps 54, adjustable lengthwise of the bar 52 and adapted to hold securely the wooden roller 56 of the mowingmachine. The end frames of the mowing machine are not shown, as the relations of the roller 56 to the reel-blades 6 and 'l, and to the machine heads2, are well known. The clamps 54 are closed by means ofbolts 58. When the roller is held by clamps 54, and the mowing-machine heads 2, 2 are held by the clamps 32, 32; the bearings 42 having been adjusted; the reel-blades 6 and 1 are in position for sharpening. By adjustment of brackets l2, arms 24, clamps 32, andof brackets'l4, and clamps 54, the position of the reel may be adjusted with respect to other parts of the machine.

The track chairs is, which may be made of short lengths of channel, are bolted down to the plates H] by the bolts 22, which terminate at their upper ends with the handles 60, and at the lower end in the threaded portion 62 which passes through a slot 64 in plate [0, and which draws up the nut or plate 66 against the underside of the plate I0, clamping it between the plate or nut adjustable as to their positions lengthwise of the 66 and the head 68. r

The long handles 64 pass axially through hollow externally threaded-studs 1B which terminate at their lower ends in plates 12, and' which are engaged at their upper ends by wing-nuts 14, which may be furnished with a washer I5. Between the wing nut 14 and the track chairs I6 'is a tie-plate I8, which rests upon the chair I6,

and on which it may be adjusted lengthwise of the chair I6. The hollow studs 10 pass through slots II in the tie-plates I8; and the tie-plates I8 are secured after adjustment by screwing down on the wing-nuts I4.

On the endwise adjustable tie-plates I6 are secured by rivets or other suitable means the two tracks 86 and 82, on which runs the carriage 84 of the grinding mechanism; the carriage being provided with shafts 86 and wheels 88 and 96. The wheels 96 are grooved to run on the edge of the narrow-headed track 82, which may be made of a small angle-bar. The wheels 88 are flat on the treads or slightly rounded and run on the broad-headed track 80; which may be made of a Z-bar to secure some stiffness.

The two tracks 8% and 82 being held firmly on the lengthwise-adjustable tie-plates I6: when the tie plates I8 are adjusted the tracks are as a unit adjusted, without changing their gauge in any way. When the tie-plate 18 is adjusted the tracks Bi] and 82 will be moved from or toward the mowing machine whose reel-blades are to be sharpened. At the end of the track chair I6 is fitted a bracket 92, which carries a finely threaded screw 94, the thread of which engages in the upright leg 96 of the track-rail 32. When the screw 94 is turned in the rail-leg 96 the whole assembly of track and tie-plate It is moved lengthwise on the track chair I6. Track adjustment is first roughly made by shifting the track chair I6 on the plate III; after which finer adjustment is made by the screw 94, to bring the abrasive wheel of the grinding mechanism into proper relation with the edge of the reel-blade to be sharpened. The adjusting features of the track chair I6 and of the tie-plate I8 are shown in enlarged detail in Figures III and IV.

The upper part of the carriage 84 is the fourcornered plate 98, in the center of which is. the pivot-pin Hill, which may be seen immediately under the electric motor I02 in the drawings.

On the carriage plate 98 there is pivoted at I ill! the plate I64 which for sake of quick identification,, and since it supports the abrasive wheel, I will term the wheel-plate. On this plate is bolted down the motor I02, which has a grooved pulley I66, a belt I68 from it which drives pulley III! which is keyed on the small shaft I I 2. This small shaft II2 runs in ball bearings mounted in the quill H4; and this quill is mounted in adjustable bearings H6 and III carried by the brackets H8, and is secured from rotation or from displacement by set-screws IIS. Mounted on the shaft H2 and at the farther end from the pulley III! is an abrasive wheel I l3 of the disk type, secured between plates I20 in the usual manner.

The adjustable bearings I I6 and I II, which are bolted to the brackets I I8, have extension arms I22, in the ends of which are circular apertures I23 through which the ends of the motor shaft are passed; the motor thus helping to keep the alignment of the bearings II6 and III. The arms I22 are extendable to allow for motor-belt adjustment. When the motor circuit is closed, and the motor runs, the abrasive wheel H3 is rotated.

on the large head I24 or the quill H4 is mounted by means of screws or bolts I26 the plate I28. shown in detail in Figure V. This plate is slotted at I36 and I32, and through these slots are passed the bolts I34 and I36.

At I38 is the reel-blade guide, the use of which is to turn the reel as the abrasive wheel passes along it. The guide is slotted about its midlength to pass around the shaft H2 and at either end to receive the bolts I34 and I35. The bladeguide I38 is adjustable lengthwise by sliding it on the bolts IM and I36, and it is adjustable in a vertical plane by raising and lowering the bolts I34 and I36 in the slots I36 and I62 respectively. Also the quill II l may be rotated after loosenin set-screws IIEI. In. this Figure V the quill I 55) bearing arm is shown at I22, and the bearing bracket at IIB.

In Figure V the shaft of the mower reel is shown at 8 in section, and three of the four blades are shown at 5 in section; the fourth blade 7 resting upon the end [31 of the blade-guide I38. The end of the guide may be straight or it may be turned at an angle to the length of the guide, as shown. The end may be of any convenient form Or as shown in Figure VI. It bears on the under side of the blade being sharpened; and as the abrasive wheel moves along the blade, which is inclined to the horizontal and is helical in form, the guide lifts the blade into proper relation with the wheel for sharpening.

The relief at the cutting edge of the blade is controlled by adjusting the position of the end I31 of the guide I38 to a level more or less above or below the center line of the abrasive wheel I I3. The wheel turns, when the mower is cutting grass. in the direction opposite to that indicated by the arrow (which is the direction of the turn when sharpening the blades); and the lower edge 1 of the blade is the cutting edge. The rotation of the cutting wheel is downward upon the blade. in" dicated by the arrow over the wheel. If the end I31 of the guide I36 be raised above the level of the center of the abrasive wheel the relief on the edge of the blade I will be negative; and if the end of the guide I36 be dropped below the level of the center of the abrasive wheel the relief of the cutting edge of the blade I will be positive, as it should be for use. I

Referring again to Figure I: the abrasive wheel II3 started its cutting action on the blade "I at its far end; and it has now traveled about one third of the length of the blade. As the abrasive wheel traveled along and sharpened the blade I. the end I31 of the guide I38 traveled along under the blade, turning the reel so that the part of the blade acted upon by the wheel was always presented at the proper angle to the wheel.

Movement of the abrasive wheel along the reelblade is preferably controlled by hand; and for that purpose a handle I49 is attached to the carriage 84.. The operator grasps the handle in his right hand, and works the carriage backward and forward along the tracks 86 and 82.

I have now described the operation of the grind-- ing machine in straight line movement along the mower-reel. If I want to grind the edge of the blade on a slight curve, from one end to the other.

I bend the track 32 on which the grooved wheel 99 runs. To bend this track I rotatably mount a threaded screw I 42 in the upright leg of the track 82. The threaded portion. of the screw I 42 engages in the drilled and threaded lug I44. which is mounted on the gusset-plate I46. which is rigidly riveted to the two bars I48. the farther ends of which are riveted to the flange of track BI]. The spread of the two bars I43 together with the stiffness of the Z-bar 86 will prevent bending of the Z-bar while a slight bend is being put in the track 82 by means of the screw I42. The preferred location of this screw is, opposite the central point of the reel-blade, so that the curve may be equal on each side of the middle of the blade. If for any reason it is desired that the high point of the curve of the blade be at some other point in the blade than the center, the mower may be shifted accordingly on the bar 52.

There are often times when hard spots are met with in reel-blades; and when it is advisable to go over a spot in a blade one or more times withoutgoing over the whole length of the blade. Attached to the wheel-plate I04 is an extended arm I50, with an upright post I52 for convenience in grasping by the hand. Remember that the wheelplate I04 is pivoted at I00. moved to the right, the abrasive wheel H3 will be moved away from the work; but on. releasing the arm I50 the wheel-plate I04 will be pulled back to its original position by the spring I54, attached at one end through an arm I56 to the motor-plate I04, and at its other end to the bracket arm I58which is secured to the carriage 84. The endof the movement of the wheelplate clockwise, on the pivot I in Fig, I, is controlled by the adjustable stop I60, which consists of a rod I6I threaded at I62 through the bracket arm I58, and having a shoulder at I64 against which the arm I56 may rest. If the threaded rod I60 is turned by the handle I66 it will be seen that the shoulder-stop I64 will be moved to the right or to the left according to the direction in which the rod I60 is turned. This admits of very fine adjustment of the wheel II3 against the reel-blade I. If we want to go over the spot in the blade more than once, we press the arm I 50 to the right to bring the wheel II3 away from the blade I; then push the carriage back bythe handle I40; and then, releasing the arm I50, allow the wheel II3 to again come into contact with the edge of the blade I. If a deeper cut is wanted this is obtained by turning the rod I60 to bring the wheel I I3 into closer contact with the blade I; and vice versa. So, the Wheel can be brought repeatedly and quick ly over any spot in the length of the blade. The blade is ground on the forward movement of the carriage 84; and for a quick return of the carriage to its starting point the wheel H3 is taken from the blade I by pressing arm I50 to the right. On release of the arm I50 the bracket I56 comes up against the shoulder I64 of the rod I60, and the wheel H3 is again in position against the blade I.

. Note that the arm I50 and the arm I56 are removable. plate I04, and on its three other sides, are notches 9, II, I3, and I5, designed to take bolts, such as the bolt 'II0 shown holding the arm I50 to the plate I04. At the farther end of the arm I50 is a fork I'IZ adapted to embrace the pivot I00 to prevent the turning of the arm I50 on the bolt II0 as on a pivot. The arm I56 to which the Spring I54 is attached is held to the plate I04 in a similar manner, except that the forked (I14) inner end of the arm I56 is held from displacement by a pin I'I6, fitting into a hole I18 in the plate I04, as shown in Figure VII, which will be described later. This is a simple and inexpensive means for attaching arms to the plate I04 so that they shall be easily and quickly removed from one location to another. To aid in the farther description of the machine let us refer to the edge of the carriage to which the handle I40 is attached as the front. The side to which the spring is attached is then the back. So also when If the arm I50 is On the curved side I68 of the wheelreferring to the plate I04, let the side to which the arm I50 is shown attached in Figure I be the front edge; let the curved edge I68 be the right edge, the edge to the left of the motor be the left edge, leaving the edge which is under the motor pulley I06 to be the rear edge.

The sharpening of the blades of large mowers may be termed heavy duty work. Mowers of this class are usually too large or too heavy to be supported in a machine of convenient size and as shown in Figures I and II; and the reel is taken from the mower, and is supported on suitable brackets attached to the plates I0. The reel will be in about the same position as that in which it is shown in Figures I and II. The light diskwheel is preferably changed to a-heavier cupwheel for the sharpening of heavy blades. The cutting edge or face of the cup-wheel lies in a plane which is normal to the axis of the wheel shaft; and so, to bring the said cutting face into proper relation to the edge of the reel-blades, we must swing the axis of the shaft I I2 through an angle of 90 degrees or thereabout so that it may be normal to the axis of the reel. I bring my wheel shaft, II 2, to this position by simply turning the plate I04 on the pivot-pin I00 through the desired angle, so that the curved right edge of the plate I 04 is at the back, and the left side of the plate is at the front; having first loosened from the plate I04 the arms I50 and I56. I now attach the said arm I50 to the left side of the plate I04, now at the front of the machine; and I attach the spring-arm I56 to the curved right side of the plate I04 which is now at the rear of the machine. This new position of the plate I04 is shown in Figure VII; in which it will be seen that the motor and allother parts carried by the plate I04 have been swung anticlockwise through 90 degrees, or approximately so, from the position shown in Figure I. But had we left the quill in the same position as in Figure I the quill head I24 and the. abrasive cup-wheel I would be turned away from the mower reel, a part of a blade of which is shown at I in Figure VII. Removing the driven pulley H0 from the small shaft II2, the quill H4 is removed from the bearings H6 and III, and its position in the said bearings is reversed, as shown in Figure VII. The driven pulley H0 is replaced upon the shaft I I2; and the motor pulley I06 is placed upon the other end of its shaft. The arm I50 is moved from the front edge of the plate I04 (as in Figure I) to the left edge of the said plate which is now at the front of the machine, as in Figure VII. In like manner the spring arm I56 is moved from the rear edge of plate I04 to the curved right edge of the said plate, which is now at the back of the machine. Note that the position of the carriage plate 98 and of the tracks 80 and 82 have not been changed; and that in Figure VII the positions of the parts of the quill head I24 are as they were in Figure I; a difference being that, since the cup-wheel I80 has been substituted for the disk-wheel H3, and the guide I38 is now pointing in a direction parallel to the reel, an auxiliary guide I02 is bolted to the guide I38. A portion of one of the heavy duty blades 1 is shown in Figure VII, resting on the auxiliary guide I82. The cup wheel is in contact with the edge of the blade I.

This arrangement of the wheel-plate I04, quillbearing H4, and the use of the cup Wheel may be used in the sharpening or grinding of the stationary cutter bar of the mower.

' Referring again to the presence of hard spots in the steel blades: were the position of the abrasive wheel rigid with respect to the blade to be sharpened, when the wheel came upon metal of a different density or hardness it might dig in, and so produce an uneven surface. This will not happen with my grinding machine; for any sudden shock to the abrasive wheel is taken up by the cushion formed by the steel spring I 54.

All operations possible when the Wheel-plate :04 was positioned as in Figure I are possible when it is turned to the position shown in Figure VII.

Though my invention is described as applied to the sharpening of the blades of mowing machines o1- lawn mowers, it is also applicable to the grinding of the teeth of cutters and to the grinding of the blades of mixing machines, and of other machines carrying reel-blades.

The carriage 84 is shown arranged for manual operation on the track 80-82. In machines of large size it can be operated mechanically if desired.

In the foregoing specification, and in the claims to follow, the term reel is used to designate the blade-reel of a mower or other machine having a rotatable reel of blades. assembly of plate, axles, and wheels designed to run along the track; the track assembly is the two rails rigidly secured to the tie-plates, and includes the track chairs upon which the tie-plates are slidably mounted; the wheel-plate is the plate The carriage is the pivoted upon the carriage plate and upon which headed rail and adapted to coact with the narrow headed rail to bend the latter; a carriage adapted to run on the track and having flanged Wheels adapted to run on and be guided by the narrow headed rail; abrasive means mounted on the carriage; means for adjusting the track tie-plates on the track chairs; and guide means adapted to support the blade and to bring it into contact with the abrasive as the latter moves along the reel.

2. In a machine for grinding mower reel blades: the combination of a base; means for supporting the reel; adjustable track chairs mounted on the base; tie-plates slidably mounted on the chairs; a two-rail track secured to the tie-plates; means for adjusting the chairs on the base to bring the track into juxtaposition with. the reel; a carriage mounted on the track and adapted to run thereon; abrasive means mounted on the carriage and comprising a wheel-plate pivoted on the carriage and adapted to be swung on the pivot during the movement of the carriage, an abrasive wheel mounted on the wheel-plate, and means for driving the abrasive wheel; meansfor adjusting the tic plates on the chairs to bring the face of the abrasive wheel into grinding contact with a blade of the reel; and guide means adapted to support the blade and to bring it into contact with the abrasive as the latter moves on the reel.

3. In a machine for grinding mower reel blades; the combination of a base; means for supporting ill the reel; adjustable track chairs mounted on the base; tie-plates slidably mounted on the chairs; a two-rail track secured to the tie-plates; means for adjusting the chairs on the base to bring the track into juxtaposition with the reel; a carriage mounted on the track and adapted to run thereon; a wheel-plate pivoted to swing on the carriage; an abrasive wheel mounted on the wheelplate with its grinding face ahead of the pivot in the direction of the forward movement of the carriage; means for driving the abrasive wheel; means for adjusting the tie-plates on the track chairs; guide means adapted to support the blade and to bring it into contact with the abrasive wheel as the wheel moves along the reel; and means for swinging the wheel-plate on its pivot to relieve the contact pressure between the face of the abrasive wheel and the blade.

4. In a machine for grinding mower reel blades:

the combination of a base; means for supporting the reel with its axis substantially parallel to the base; a track mounted on the base; means for adjusting the track to bring it into juxtaposition with the reel; a carriage mounted on the track and adapted to run thereon; a wheel-plate pivoted to swing on the carriage; an abrasive wheel mounted on the wheel-plate with its grinding face ahead of the pivot in the direction of the forward movement of the carriage; means for driving the abrasive wheel; guide means adapted to support the blade and to bring it into contact with the abrasive wheel as the wheel moves along the reel; means for swinging the wheel-plate on its pivot to relieve the contact pressure between the face of the abrasive wheel and the blade; and adjustable means for limiting the arc of the swing of the wheel-plate.

5. In a machine for grinding mower reel blades: the combination of a base; means for supporting the reel with its axis substantially parallel to the base; a track mounted on the base; means for adjusting the track to bring it into juxtaposition with the reel; a carriage mounted on the track and adapted to run thereon; a wheel-plate pivotally mounted on the carriage; brackets spaced apart upon the wheel-plate; arms vertically adjustable on the brackets; a quill bearing mounted in the arms; a shaft mounted to rotate in the quill bearing; an abrasive wheel mounted on the shaft; means for driving the abrasive wheel; and uidemeans adapted to support the blade and to bring it into contact with the abrasive wheel as the wheel moves along the reel.

6. In a machine for grinding mower reel blades: the combination of a base; means for supporting the reel; a track mounted on the base; means for adjusting the track to bring it into juxtaposition with the reel blade; a carriage mounted on the track and adapted to run thereon; a wheel-plate pivotally mounted on the carriage; brackets spaced apart upon the wheel-plate; arms vertically adjustable upon the brackets; a quill bearing mounted in the arms; a shaft mounted to rotate in the quill bearing; an abrasive wheel mounted on the shaft; means for driving the abrasive wheel; and a finger-guide adapted to engage the underside of the blade being processed to hold it in contact with the wheel as the latter moves along the reel, the said finger-guide being radially disposed from the center of the wheel and also being adjustable as to its height. relative to the center of the wheel.

direction of the forward movement of the carriage; means for bringing the grinding face of the Wheel into grinding contact with the reel blade; and elastic means coacting with the pivoted plate to relieve the wheel from excessive pressure arising between the wheel and the blade.

CHARLES F. BROWN. 

